A. Perkins, Wenhua Yang, Yucheng Liu, Lei Chen, C. Yenusah
Porosity has been known to have a profound effect on a material’s mechanical properties, often weakening the material. Highly porous metallic materials prove troublesome for supporting a load-based structure due to the voids that are present throughout the microstructure of the material. In this study, the previously developed ISV damage plasticity model is used to investigate the effect of the porosity on aluminum alloy 6061-T651 and magnesium alloy AZ31 through finite element analysis (FEA). It is determined that porosity has a profound impact on the strength of the aluminum alloy and much lesser effect on the magnesium alloy. Porosity is also shown to affect other properties of the materials, such as the hardness and pore growth.
{"title":"Finite Element Analysis of the Effect of Porosity on the Plasticity and Damage Behavior of Mg AZ31 and Al 6061 T651 Alloys","authors":"A. Perkins, Wenhua Yang, Yucheng Liu, Lei Chen, C. Yenusah","doi":"10.1115/imece2019-10672","DOIUrl":"https://doi.org/10.1115/imece2019-10672","url":null,"abstract":"\u0000 Porosity has been known to have a profound effect on a material’s mechanical properties, often weakening the material. Highly porous metallic materials prove troublesome for supporting a load-based structure due to the voids that are present throughout the microstructure of the material. In this study, the previously developed ISV damage plasticity model is used to investigate the effect of the porosity on aluminum alloy 6061-T651 and magnesium alloy AZ31 through finite element analysis (FEA). It is determined that porosity has a profound impact on the strength of the aluminum alloy and much lesser effect on the magnesium alloy. Porosity is also shown to affect other properties of the materials, such as the hardness and pore growth.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114322354","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper concerns with the coupled linear theory of thermoelasticity for porous materials and the coupled phenomena of the concepts of Darcy’s law and the volume fraction is considered. The system of governing equations based on the equations of motion, the constitutive equations, the equation of fluid mass conservation, Darcy’s law for porous materials, Fourier’s law of heat conduction and the heat transfer equation. The system of general governing equations is expressed in terms of the displacement vector field, the change of volume fraction of pores, the change of fluid pressure in pore network and the variation of temperature of porous material. The fundamental solution of the system of steady vibration equations is constructed explicitly by means of elementary functions and its basic properties are presented. The basic internal and external boundary value problems (BVPs) of steady vibrations are formulated and on the basis of Green’s identities the uniqueness theorems for the regular (classical) solutions of the BVPs are proved. The surface (single-layer and double-layer) and volume potentials are constructed and their basic properties are established. Finally, the existence theorems for classical solutions of the BVPs of steady vibrations are proved by means of the boundary integral equations method (potential method) and the theory of singular integral equations.
{"title":"Boundary Integral Equations Method in the Coupled Theory of Thermoelasticity for Porous Materials","authors":"M. Svanadze","doi":"10.1115/imece2019-10367","DOIUrl":"https://doi.org/10.1115/imece2019-10367","url":null,"abstract":"\u0000 This paper concerns with the coupled linear theory of thermoelasticity for porous materials and the coupled phenomena of the concepts of Darcy’s law and the volume fraction is considered. The system of governing equations based on the equations of motion, the constitutive equations, the equation of fluid mass conservation, Darcy’s law for porous materials, Fourier’s law of heat conduction and the heat transfer equation. The system of general governing equations is expressed in terms of the displacement vector field, the change of volume fraction of pores, the change of fluid pressure in pore network and the variation of temperature of porous material. The fundamental solution of the system of steady vibration equations is constructed explicitly by means of elementary functions and its basic properties are presented. The basic internal and external boundary value problems (BVPs) of steady vibrations are formulated and on the basis of Green’s identities the uniqueness theorems for the regular (classical) solutions of the BVPs are proved. The surface (single-layer and double-layer) and volume potentials are constructed and their basic properties are established. Finally, the existence theorems for classical solutions of the BVPs of steady vibrations are proved by means of the boundary integral equations method (potential method) and the theory of singular integral equations.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"21 9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126059648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A closed guardrail system, known as “bullnose” guardrail system, was previously developed to prevent out-of-control vehicles from falling into the elephant trap. The bullnose guardrail system originally used Controlled Release Terminal (CRT) wood posts to aid in the energy absorption of the system. However, the use of CRT had several drawbacks such as grading and the need for regular inspections. Universal Breakaway Steel Post (UBSP) was then developed by the researchers at Midwest Roadside Safety Facility as a surrogate for CRT. In this study, the impact performance of UBSP on the weak-axis and strong-axis was studied through numerical modeling and component testing (bogie testing). A numerical model was developed using an advanced finite element package LS-DYNA to simulate the impact on UBSP. The numerical results were compared to experimental data. Further research on soil models was recommended. The numerical model will be used to investigate other applications for UBSP such as the Midwest Guardrail System (MGS) long span system, guardrail end terminal designs, or crash cushions.
{"title":"Experimental and Numerical Investigation of Dynamic Impact on Universal Breakaway Steel Post","authors":"J. Mehrmashhadi, M. A. Pajouh, J. D. Reid","doi":"10.1115/imece2019-12209","DOIUrl":"https://doi.org/10.1115/imece2019-12209","url":null,"abstract":"\u0000 A closed guardrail system, known as “bullnose” guardrail system, was previously developed to prevent out-of-control vehicles from falling into the elephant trap. The bullnose guardrail system originally used Controlled Release Terminal (CRT) wood posts to aid in the energy absorption of the system. However, the use of CRT had several drawbacks such as grading and the need for regular inspections. Universal Breakaway Steel Post (UBSP) was then developed by the researchers at Midwest Roadside Safety Facility as a surrogate for CRT. In this study, the impact performance of UBSP on the weak-axis and strong-axis was studied through numerical modeling and component testing (bogie testing). A numerical model was developed using an advanced finite element package LS-DYNA to simulate the impact on UBSP. The numerical results were compared to experimental data. Further research on soil models was recommended. The numerical model will be used to investigate other applications for UBSP such as the Midwest Guardrail System (MGS) long span system, guardrail end terminal designs, or crash cushions.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129533189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The braking performance of the vehicle directly affects the driving safety. Because of the different number of brake pistons and the wear of the brake pads, the distribution of braking pressure will be uneven, which will affect the distribution of temperature field and stress field during braking, then affect the thermal fatigue life of brake discs. Therefore, in this paper, the static tensile and compressive tests of gray cast iron HT200 samples cut from vehicle brake discs are carried out at −25°C, room temperature (25°C) and 500°C, and the stress-strain curves are analyzed to obtain mechanical properties such as strength limit, elastic modulus and so on at the temperature. Based on these parameters, the finite element software ABAQUS is used to simulate the single emergency braking condition. The thermal-structural coupling simulation of brake disc is carried out to study the influences of uneven brake pressure distribution on the temperature and stress fields of brake disc, which lays a foundation for the thermal fatigue life evaluation of brake disc.
{"title":"Effects of Braking Pressure Distribution on Temperature Field and Stress Field During Braking","authors":"Xianyu Zeng, Yu Liu, Xiandong Liu, Yingchun Shan, Yue Zhang, Xiaoran Wang","doi":"10.1115/imece2019-10379","DOIUrl":"https://doi.org/10.1115/imece2019-10379","url":null,"abstract":"\u0000 The braking performance of the vehicle directly affects the driving safety. Because of the different number of brake pistons and the wear of the brake pads, the distribution of braking pressure will be uneven, which will affect the distribution of temperature field and stress field during braking, then affect the thermal fatigue life of brake discs. Therefore, in this paper, the static tensile and compressive tests of gray cast iron HT200 samples cut from vehicle brake discs are carried out at −25°C, room temperature (25°C) and 500°C, and the stress-strain curves are analyzed to obtain mechanical properties such as strength limit, elastic modulus and so on at the temperature. Based on these parameters, the finite element software ABAQUS is used to simulate the single emergency braking condition. The thermal-structural coupling simulation of brake disc is carried out to study the influences of uneven brake pressure distribution on the temperature and stress fields of brake disc, which lays a foundation for the thermal fatigue life evaluation of brake disc.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128880338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Adewale Olasumboye, G. Owolabi, O. A. Koya, H. Whitworth, N. Yilmaz
This study investigates the dynamic response of AA2519 aluminum alloy in T6 temper condition during plastic deformation at high strain rates. The aim was to determine how the T6 temper condition affects the flow stress response, strength properties and microstructural morphologies of the alloy when impacted under compression at high strain rates. The specimens (with aspect ratio, L/D = 0.8) of the as-cast alloy used were received in the T8 temper condition and further heat-treated to the T6 temper condition based on the standard ASTM temper designation procedures. Split-Hopkinson pressure bar experiment was used to generate true stress-strain data for the alloy in the range of 1000–3500 /s strain rates while high-speed cameras were used to monitor the test compliance with strain-rate constancy measures. The microstructures of the as received and deformed specimens were assessed and compared for possible disparities in their initial microstructures and post-deformation changes, respectively, using optical microscopy. Results showed no clear evidence of strain-rate dependency in the dynamic yield strength behavior of T6-temper designated alloy while exhibiting a negative trend in its flow stress response. On the contrary, AA2519-T8 showed marginal but positive response in both yield strength and flow behavior for the range of strain rates tested. Post-deformation photomicrographs show clear disparities in the alloys’ initial microstructures in terms of the second-phase particle size differences, population density and, distribution; and in the morphological changes which occurred in the microstructures of the different materials during large plastic deformation. AA2519-T6 showed a higher susceptibility to adiabatic shear localization than AA2519-T8, with deformed and bifurcating transformed band occurring at 3000 /s followed by failure at 3500 /s.
{"title":"Comparative Study of the Dynamic Behavior of AA2519 Aluminum Alloy in T6 and T8 Temper Conditions","authors":"Adewale Olasumboye, G. Owolabi, O. A. Koya, H. Whitworth, N. Yilmaz","doi":"10.1115/imece2019-10978","DOIUrl":"https://doi.org/10.1115/imece2019-10978","url":null,"abstract":"\u0000 This study investigates the dynamic response of AA2519 aluminum alloy in T6 temper condition during plastic deformation at high strain rates. The aim was to determine how the T6 temper condition affects the flow stress response, strength properties and microstructural morphologies of the alloy when impacted under compression at high strain rates. The specimens (with aspect ratio, L/D = 0.8) of the as-cast alloy used were received in the T8 temper condition and further heat-treated to the T6 temper condition based on the standard ASTM temper designation procedures. Split-Hopkinson pressure bar experiment was used to generate true stress-strain data for the alloy in the range of 1000–3500 /s strain rates while high-speed cameras were used to monitor the test compliance with strain-rate constancy measures. The microstructures of the as received and deformed specimens were assessed and compared for possible disparities in their initial microstructures and post-deformation changes, respectively, using optical microscopy. Results showed no clear evidence of strain-rate dependency in the dynamic yield strength behavior of T6-temper designated alloy while exhibiting a negative trend in its flow stress response. On the contrary, AA2519-T8 showed marginal but positive response in both yield strength and flow behavior for the range of strain rates tested. Post-deformation photomicrographs show clear disparities in the alloys’ initial microstructures in terms of the second-phase particle size differences, population density and, distribution; and in the morphological changes which occurred in the microstructures of the different materials during large plastic deformation. AA2519-T6 showed a higher susceptibility to adiabatic shear localization than AA2519-T8, with deformed and bifurcating transformed band occurring at 3000 /s followed by failure at 3500 /s.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121587638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The goal of this paper is to find the best impact response of the composite sandwich panels with honeycomb core. The focus of the study is to find the effects of changing the face sheet thickness and the core height of the sandwich panel subjected to variable velocities on impact performance. Initially, honeycomb core sandwich panel with 1mm thick face sheet is modelled in Abaqus/explicit to calculate the energy absorption, residual velocity, and deformation at four different velocities. Then, the process is repeated by changing the face sheets thickness to 2mm and 3mm to see the effects of changing the thickness on the impact performance of a composite sandwich panel. The honeycomb core height is also changed to see its effect on the performance. In all models, Al 7039 is used in the core and T1000G is used in the face sheets.
{"title":"Numerical Modelling of Impact Behavior of Composite Sandwich Panel With Honeycomb Core","authors":"S. Alam, Aakash Bungatavula","doi":"10.1115/imece2019-11721","DOIUrl":"https://doi.org/10.1115/imece2019-11721","url":null,"abstract":"\u0000 The goal of this paper is to find the best impact response of the composite sandwich panels with honeycomb core. The focus of the study is to find the effects of changing the face sheet thickness and the core height of the sandwich panel subjected to variable velocities on impact performance. Initially, honeycomb core sandwich panel with 1mm thick face sheet is modelled in Abaqus/explicit to calculate the energy absorption, residual velocity, and deformation at four different velocities. Then, the process is repeated by changing the face sheets thickness to 2mm and 3mm to see the effects of changing the thickness on the impact performance of a composite sandwich panel. The honeycomb core height is also changed to see its effect on the performance. In all models, Al 7039 is used in the core and T1000G is used in the face sheets.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134328717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Composites including carbon nanotubes are of great value due to their thermal, electrical and mechanical properties. They have a wide range of uses in the structural and electrical/electronic industry due to their high strength to weight ratio and high conductivity. Here we study the effect of carbon nanotube waviness and volume fraction on the damping properties of a polymer composite. The analysis is done using the finite element method over a representative volume element which consists of carbon nanotubes as inclusions dispersed in a viscoelastic matrix. The carbon nanotubes are of similar density as the matrix but have a higher modulus of elasticity. This study analyzes the effect of change in volume fraction and waviness of the nanotubes on the damping properties when subjected to a range of vibration frequencies under mixed boundary conditions. This study also analyzes the effect of two different loading direction while keeping the boundary conditions the same. It has been observed that the damping capacity of the composite is greatly dependent on applied loading frequency. Also, the damping capacity of composite decreases significantly as the volume fraction of nanotubes increases. The waviness of nanotubes also has a similar effect on damping property of composite as of volume fraction of nanotubes.
{"title":"Study of the Effect of Carbon Nano-Tube Waviness and Volume Fraction on the Damping Property of a Polymer Composite","authors":"S. Kulkarni, A. Tabarraei, Satyam Shukla","doi":"10.1115/imece2019-11843","DOIUrl":"https://doi.org/10.1115/imece2019-11843","url":null,"abstract":"\u0000 Composites including carbon nanotubes are of great value due to their thermal, electrical and mechanical properties. They have a wide range of uses in the structural and electrical/electronic industry due to their high strength to weight ratio and high conductivity. Here we study the effect of carbon nanotube waviness and volume fraction on the damping properties of a polymer composite. The analysis is done using the finite element method over a representative volume element which consists of carbon nanotubes as inclusions dispersed in a viscoelastic matrix. The carbon nanotubes are of similar density as the matrix but have a higher modulus of elasticity. This study analyzes the effect of change in volume fraction and waviness of the nanotubes on the damping properties when subjected to a range of vibration frequencies under mixed boundary conditions. This study also analyzes the effect of two different loading direction while keeping the boundary conditions the same. It has been observed that the damping capacity of the composite is greatly dependent on applied loading frequency. Also, the damping capacity of composite decreases significantly as the volume fraction of nanotubes increases. The waviness of nanotubes also has a similar effect on damping property of composite as of volume fraction of nanotubes.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115963456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thin walled members are commonly used in vehicle’s frontal chassis to provide protection and damage attenuation to the passenger cabin in the case of an impact loading. These structural members undergo progressive deformation under axial loading. The type of deformation mode is critical as it defines the overall configuration of force-displacement curve. There are different types of deformation modes for cross tubes under axial loading. Likewise, the cellular structures exhibit distinct deformation modes under in-plane loading. The work presented here investigates the effects of bonding of cellular core structure on deformation modes of cross tubes under axial loading. The results show that partial, or discrete bonding of cellular core with the tube has significant effect on progressive deformation of tubes and therefore, presents an opportunity to re-configure force-displacement curve for improved protection of automobile structures under impact loading.
{"title":"Dynamic Behavior of Discretely Bonded Cross Tube With Functionally Graded Cellular Structure","authors":"S. Jenson, E. Ohioma, Muhammad Ali, K. Alam","doi":"10.1115/imece2019-10753","DOIUrl":"https://doi.org/10.1115/imece2019-10753","url":null,"abstract":"\u0000 Thin walled members are commonly used in vehicle’s frontal chassis to provide protection and damage attenuation to the passenger cabin in the case of an impact loading. These structural members undergo progressive deformation under axial loading. The type of deformation mode is critical as it defines the overall configuration of force-displacement curve. There are different types of deformation modes for cross tubes under axial loading. Likewise, the cellular structures exhibit distinct deformation modes under in-plane loading. The work presented here investigates the effects of bonding of cellular core structure on deformation modes of cross tubes under axial loading. The results show that partial, or discrete bonding of cellular core with the tube has significant effect on progressive deformation of tubes and therefore, presents an opportunity to re-configure force-displacement curve for improved protection of automobile structures under impact loading.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117244964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Construction industry is about to embrace 3D printing as a viable technology for fabricating structures that are not physically or commercially impractical. These include curved components that could be embedded in buildings. On the other hand, whole house building by 3D printing has been attempted around the world using giant concrete printers. The main question is how to integrate steel rebars in concrete by 3D welding and still maintain the structural integrity and reliability of the conventional rebars. To accomplish the incorporation of rebars in concrete, steel must be welded within concrete. Heat dissipation rates may be different in different directions when the 3D molten weld pool solidifies, especially when the substrate is concrete. This may affect the strength of the material along and across the weld bead. To investigate this effect, it is important to study the mechanical properties of 3D welded steel in the directions of length, thickness and width. Experiments conducted in this study include the 3D welding of steel on concrete tiles by attaching the torch of a MIG welder to a meter-scale 3D printer carriage. The weld beads were then cross sections in directions along the weld bead, across the bead and perpendicular to the ceramic substrate. Dog-bone shaped micro-scale samples were extracted along those direction by CNC machining and EDM milling. The specimens were then mounted on the grippers of a hybrid micro-tester and tensile tests were carried out. The results of the tests are reported, and the implications of the findings in terms of the feasibility of 3D printing of steel reinforced concrete are discussed.
{"title":"Mechanical Properties of Steel Printed on Ceramics","authors":"S. Allameh, Miguel Ortiz Rejon","doi":"10.1115/imece2019-10392","DOIUrl":"https://doi.org/10.1115/imece2019-10392","url":null,"abstract":"\u0000 Construction industry is about to embrace 3D printing as a viable technology for fabricating structures that are not physically or commercially impractical. These include curved components that could be embedded in buildings. On the other hand, whole house building by 3D printing has been attempted around the world using giant concrete printers. The main question is how to integrate steel rebars in concrete by 3D welding and still maintain the structural integrity and reliability of the conventional rebars. To accomplish the incorporation of rebars in concrete, steel must be welded within concrete. Heat dissipation rates may be different in different directions when the 3D molten weld pool solidifies, especially when the substrate is concrete. This may affect the strength of the material along and across the weld bead. To investigate this effect, it is important to study the mechanical properties of 3D welded steel in the directions of length, thickness and width. Experiments conducted in this study include the 3D welding of steel on concrete tiles by attaching the torch of a MIG welder to a meter-scale 3D printer carriage. The weld beads were then cross sections in directions along the weld bead, across the bead and perpendicular to the ceramic substrate. Dog-bone shaped micro-scale samples were extracted along those direction by CNC machining and EDM milling. The specimens were then mounted on the grippers of a hybrid micro-tester and tensile tests were carried out. The results of the tests are reported, and the implications of the findings in terms of the feasibility of 3D printing of steel reinforced concrete are discussed.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125301786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Double network (DN) elastomers are a class of reinforced gels that benefit from a significantly high stretch-ability and toughness. However, DN gels lose their toughness due to the accumulation of damage under cyclic loading during their lifetime. While recent advances in the process and characterization of the DN gels have led to significant improvements in their properties, our understandings of the accumulated damage mechanisms within the material remain sparse and inconclusive. Here, a physically motivated constitutive model is presented for DN gels subjected to a high number of cyclic deformations, which will eventually approach a steady-state after thousands of cycles. The model can be particularly used to elucidate the inelastic features, such as permanent damage during deformation of each cycle. The observed damage may be induced from the chain scission, chain slippage, or polymer relaxation. Therefore, irreversible chain detachment and decomposition of the first network due to its highly cross-linked structure are explored as the underlying reasons for the nonlinear stress softening phenomenon. The model is validated against the experimental tests. The model contains a few numbers of material constants and shows good agreement with cyclic uni-axial tensile test data.
{"title":"Modelling Damage Accumulation During Cyclic Loading in Elastomeric Gels With Interpenetrating Networks","authors":"V. Morovati, R. Dargazany","doi":"10.1115/imece2019-11931","DOIUrl":"https://doi.org/10.1115/imece2019-11931","url":null,"abstract":"\u0000 Double network (DN) elastomers are a class of reinforced gels that benefit from a significantly high stretch-ability and toughness. However, DN gels lose their toughness due to the accumulation of damage under cyclic loading during their lifetime. While recent advances in the process and characterization of the DN gels have led to significant improvements in their properties, our understandings of the accumulated damage mechanisms within the material remain sparse and inconclusive. Here, a physically motivated constitutive model is presented for DN gels subjected to a high number of cyclic deformations, which will eventually approach a steady-state after thousands of cycles. The model can be particularly used to elucidate the inelastic features, such as permanent damage during deformation of each cycle. The observed damage may be induced from the chain scission, chain slippage, or polymer relaxation. Therefore, irreversible chain detachment and decomposition of the first network due to its highly cross-linked structure are explored as the underlying reasons for the nonlinear stress softening phenomenon. The model is validated against the experimental tests. The model contains a few numbers of material constants and shows good agreement with cyclic uni-axial tensile test data.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122609743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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